Electrodeposition of nickel

ABSTRACT

AN AQUEOUS ACIDIC BATH SOLUTION FOR ELECTROPLATING NICKEL INCLUDES AT LEAST ONE NICKEL SALT AS A SOURCE OF NICKEL AND, AS A BRIGHTENER, A COMBINATION OF AN OXYETHYLENATED SULFOLENE COMPOUND AND A WATER-SOLUBLE ALLYL SULFONATE IN AN AMOUNT SUFFICIENT TO PRODUCE A BRIGHT NICKEL ELECTRODEPOSIT.

United States Patent 3,709,798 ELECTRODEPOSITION 0F NICKEL Joseph R.Duchene, Southfield, Mich., assiguor to The Richardson Chemical Company,Baltimore, Md.

N 0 Drawing. Continuation-impart of application Ser. No. 52,083, July 2,1970. This application Oct. 13, 1971, Ser. No. 188,771

Int. Cl. C23b 5/08 US. Cl. 20449 3 Claims ABSTRACT OF THE DISCLOSURE Anaqueous acidic bath solution for electroplating nickel includes at leastone nickel salt as a source of nickel and, as a brightener, acombination of an oxyethylenated sulfolene compound and a water-solubleallyl sulfonate in an amount sufficient to produce a bright nickelelectrodeposit.

This application is a continuation-in-part of my application S.N.52,083, filed July 2, 1970.

This invention relates to the electrodeposition of nickel and moreparticularly to electroplating solutions adapted to produce full brightnickel deposits. The bright nickel deposit produced according to thisinvention exhibits improved ductility and throwing or coveringcharacteristics and thus is capable of improved coverage ofimperfections in the base metal.

It has now been found that improved full bright, ductile nickel depositscan be obtained using an aqueous acidic nickel plating bath havingincorporated therein a brightening system comprising a combination of anoxyethylenated sulfolene compound and a water-soluble allyl sulfonate.

It has been known to modify nickel electroplating baths with brighteningagents as well as with agents to improve leveling effects. The use ofnickel plating baths containing a sulfolene compound, such as sulfolanylether as a brightening agent is disclosed for instance in US. Pat.3,376,207. It was found, however, that in order to obtain a full brightnickel deposit to the degree desired, the said sulfolene compounds ofthis reference, for instance, hydroxy butyne sulfolanyl ether, had to bemodified by the addition thereto of nitrogen or a nitrogen typebrightener, such as an imidizol, and an aromatic carrier such as sodiumsaccharin or 1,3,6-naphthalene trisulfonic acid, sodium salt to obtain afull bright nickel deposit. However, the addition of these materialsoften produced deleterious effects with respect to the ductility andhardness of the subsequent nickel deposit. The breakdown products ofnitrogen bearing compounds can be particularly deleterious, causingstresses in the subsequent nickel deposit. Accordingly, where ductilityand hardness are desirable or the necessary characteristics, the use ofsuch combinations of materials in the plating bath did not appearadvisable.

It was then found that such disadvantages could be overcome by includingin the aqueous acidic nickel plating bath a brightening agent consistingessentially of a sulfolene compound in combination with a watersolubleallyl sulfonate as disclosed in my copending application S.N. 52,083. Itwas also found that this combination of materials, i.e. the sulfolenecompound and the water-soluble allyl sulfonate exhibited a synergisticeffect and that this combination produced superior nickelelectrodeposits when compared, for instance, to earlier known additives.Additionally, it was found that the novel plating baths disclosed in myaforementioned application also provided desirable results in theabsence 3,709,798 Patented Jan. 9, 1973 of any conventional nitrogencontaining compounds and any aromatic sulfur compounds.

As an improvement on the invention disclosed in S.N. 52,083 there is nowprovided a novel plating bath which includes as a brightening agent anoxyethylenated sulfolene compound in combination with a water-solubleallyl snlfonate. This combination of components provides an even higherluster to the resulting nickel deposit and the brightener itselfexhibits markedly improved stability characteristics. The preferredbrightening agent system employed in the present invention is thereaction product of 3-sulfolene with 1,4-di-(2-hydroxyethoxy) butyne-2,or 2-butyne 1,4 diol oxyethylenated with 2 mols of ethylene oxide incombination with sodium allyl sulfonate, although, as the oxyethylenatedsulfolene compound the following materials can also be usefullyemployed: the reaction product of 3-sulfolene with a member selectedfrom the group consisting of propargyl alcohol, Z-butyne- 1-ol,4-methoxy-2-butyne-1-ol, 3-hexyne-2,5-diol, 3-pentyene-l-ol and2,4-hexadiyne-1,6-diol, said member being oxethylenated with 2 moles ofethylene oxide.

The novel brightening agent of this invention is generally used in theamounts between 1.5 to 5 grams of sodium allyl sulfonate per liter ofbath solution and 0.01 to 1.0 gram of the oxyethylenated sulfolenecompound per liter of bath solution.

In general, the process of this invention involves operating a bath atconventional nickel plating temperatures ranging from about room toboiling, though usually most convenient temperatures of operation arefrom about F. to 170 F. The best pH values for the bath range from about3.5 to 4.5 though a pH as low as 2 and as high as 6 can also beemployed. Preferably, the pH will range between 3.0 and 5.0 in themajority of the cases. The cathodic current densities to be used averagegenerally from about 1 to 200 amp/sq. ft. depending, for instance, onthe temperature, degree of solution agitation and the composition of thebath. Higher temperatures and more rapid agitation permit higher currentdensities to be used effectively.

Baths for electroplating in accordance with this invention contain atleast one nickel salt as a source of nickel and include well-knownWatts-type bath and high chloride type bath. The Watts bath solutiontypically comprises around 200'400 grams/liter of nickel sulfate, 30- 75grams/liter of nickel chloride and 3050 grams/liter of boric acid. Ahigh chloride type bath can contain about -300 grams/liter of nickelchloride, 40-150 grams/liter of nickel sulfate and 3050 grams/liter ofboric acid. Considerable latitude is also permissible in respect to thetypes and concentrations of the nickel salts employed. For instance, asthe source of nickel, nickel sulfamate as well as a combination ofnickel fluoborate with nickel sulfate and nickel chloride or acombination of nickel fiuoborate with nickel chloride can be employed.

Additionally, the bath can include other brighteners. However, suchother brighteners are not necessary to obtain the full bright, ductilenickel deposits of this invention. Examples of other brighteners whichcan be used in addition to the novel brighteners of this inventioninclude aliphatic sulfur compounds such as methallyl sulfonate,2-butene, l-chloro, 4-sulfonate and Z-butene, 1,4- disulfonic acid.Generally, when used, such aliphatic sulfur compounds can be present inamounts ranging from 0.1 to 10 grams/liter of solution.

Additionally, water-soluble acetylenic compounds can also be effectivelyincluded in the bath solution of this invention. The acetyleniccompounds include 2-butyne-1, 4-diol, 4-methoxy-2-butyn-1-ol,3-hexyne-2, S-diol, 3- pentyn-l-ol, 2,4-hexadiyne-1, 6-diol.Conveniently, the

water-soluble acetylenic compound can be employed in amounts rangingfrom about 0.01 to 0.03 gram/liter of solution.

For the purpose of giving those skilled in the art a betterunderstanding of the invention, the following illustrative examples aregiven in which the aqueous acidic nickelcontaining bath was made up withspecified components. Electrodeposition was carried out by passingelectric current through an electric circuit comprising an anode and asheet metal or rod cathode, both immersed in the bath. The bath wasagitated, usually by moving the cathode although, in certain instances,air agitation or other mechanical or electrical agitation means can beemployed.

In the examples, the below described standard Watts-type bath was usedas a base solution and a standard 267 ml. hull cell was used as theplating cell:

Nickel sulfate, 02/ gal. 40 Nickel chloride, oz./ gal 8 Boric acid, oz./gal 6 pH 4.0-4.2 Temperature, F 140 Current, amperes 2 Time, min lAgitation, strokes/min. 4050 To illustrate the synergistic efiect of thecombination of the oxyethylenated sulfolene compound and water-solubleallyl sulfonate, Examples 13 below are provided.

EXAMPLE 1 G./l. Reaction product of 3-su1folene and 2-butyne 1,4-dioloxyethylenated with 2 moles ethylene oxide 0.05

EXAMPLE 2 G./l. Sodium allyl sulfonate 3 EXAMPLE 3 G./l. Reactionproduct otf 3-sulfolene and Z-butyne 1,4-diol oxyethylenated with 2moles ethylene oxide 0.05 Sodium allyl sulfonate 3 Steel panels, nickelplated with the respective baths defined above, exhibited, only in thecase where both an oxyethylenated sulfolene compound and a water-solubleallyl sulfonate were used, i.e. Example 3, a full bright, level andductile electrodeposit over the whole current density range. Theelectrodeposits resulting from both Examples 1 and 2 were significantlyinferior with respect, for instance, to the brightening characteristicsachieved with the brightening agent employed in Example 3.

Examples 4-6 and 89 illustrate that the advantages of the presentinvention also are not achieved when the ingredients making up thecombination of materials of this invention are used, singly or incombination, with conventionally employed nitrogen bearing or aromaticsultfur containing brightening agents or when these conventionalbrightening agents are employed alone. Examples 4-6 and 810 whencompared to Example 7 or Example 3 which employ the brightening agent ofthis invention, fail to provide the advantages attained by the presentinvention.

EXAMPLE 4 Saccharin 1 EXAMPLE 5 Reaction product of 3-sulfolene with2-butyne 1,4-

diol oxyethylenate with 2 moles ethylene oxide 0.05

Saccharin 1 EXAMPLE 6 Sodium allyl sulfonate 3 Saccharin 1 4 EXAMPLE 7G./l. Reaction product of 3-sulfolene with Z-butyne 1,4-

diol oxyethylenated with 2 moles ethylene oxide 0.05

Sodium allyl sulfonate 3 Saccharin 1 EXAMPLE 8 1,3,6-napl1thalenetrisulfonic acid, sodium salt 4 EXAMPLE 9 1,3,6-naphthalene trisultfonicacid, sodium salt 4 Reaction product of 3-sulfolene with Z-butyne 1,4-

diol oxyethylenated with 2 moles ethylene oxide 0.05

EXAMPLE l0 G./l. 1,3,6-naphthalene trisulfonic acid, sodium salt 4Reaction product of 3-sulfolene with 2-butyne 1,4-

diol oxyethylenated with 2 moles ethylene oxide 0.05 Sodium allylsulfonate 3 Examples 11-18 are provided to illustrate the use ofoxyethylenated sulfolene compounds other than that obtained by thereaction of 3-sulfolene with 2-butyne 1,4-diol oxyethylenated with 2moles ethylene oxide in combination with sodium allyl sulfonate and toillustrate varying proportions of each while still achieving the desiredresults of the present invention.

EXAMPLE 11 G./l. Reaction product of 3-sulfolene with 2 butene-1,4-

diol oxyethylenated with 2 moles ethylene oxide 0.05 Sodium allylsulfonate 1.5

EXAMPLE 12 G./1. Reaction product of 3-sulfolene with propargyl alcoholoxyethylenated with 2 moles ethylene oxide 0.03

EXAMPLE l3 G./l. Reaction product of 3-sulfolene with 2-butyne-l-oloxyethylenated with 2 moles ethylene oxide 0.05 Sodium allyl sulfonate 3EXAMPLE 14 G./l. Reaction product of 3-sulfolene with 4-methoxy2-butyne-1-ol oxyethylenated with 2 moles ethylene oxide 0.1 Sodiumallyl sulfonate 3 EXAMPLE 1S Reaction product of 3-sulfolene with3-hexyne-2,5-

diol oxyethylenated with 2 moles ethylene oxide 0.01

Sodium allyl sulfonate 1.5

EXAMPLE l6 G./l. Reaction product of 3-sulfolene with 3-pentyne-1-Oloxyethylenated with 2 moles ethylene oxide 0.01 Sodium allyl sulfonate 5EXAMPLE 17 G./l. Reaction product of 3-sulfolene with 2,4-hexadiyne-1,6-diol oxyethylenated with 2 moles ethylene oxide 1 Sodium allylsulfonate 1.5

Unless otherwise specified, all parts and percentages in thespecification and claims are by weight. The foregoing examplesillustrate specific baths and processes, several being preferred. It isto be understood that the compositions and conditions can be varied. Forinstance,

other aqueous acidic bath solutions can be used in place of theWatts-type bath mentioned above. For example, substantially equallyfavorable results can be attained using a virging sulfamate nickel bathinstead of the Watts bath specified above.

What is claimed is:

1. An aqueous acidic electroplating bath solution for producing a brightnickel deposit consisting essentially of at least one nickel salt as asource of nickel and, as a brightener, a combination of anoxyethylenated sulfolene compound which is the reaction product of 3-sulfolene with a member selected from the group consisting of Z-butyne1,4-diol, 2-butyne-1-ol, 4-methoxy-2 butyne-l-ol, 3-hexyne-2,5-diol,3-pentyne-1-ol and 2,4- hexadiyne-1,6-diol, said member beingoxyethyleuated with 2 moles of ethylene oxide and a water-soluble allylsulfonate wherein the oxyethylenated sulfolene compound is present inamounts from 0.01 to 1.0 g./l. and the water-soluble allyl sulfonate ispresent in amounts from 1.5 to 5 g./l.

2. The electroplating bath of claim 1 wherein the oxyethylenatedsulfolene compound is the reaction product References Cited UNITEDSTATES PATENTS 2,550,449 4/ 1951 Brown 20449 3,334,032 8/1967 Kardos20449 3,376,207 4/1968 Ericson 20449 3,399,123 8/1968 Passel 204493,413,295 11/1968 Passel et a1. 20449 3,639,220 2/1972 Fuchs et al.20449 F. C. EDMUNDSON, Primary Examiner U.S. Cl. X.R. 204Dig. 2

